1. Field of the Invention
This invention relates to an improvement in processes for producing approximately spherical-shaped self-dispersing ionomer resins and, more particularly, to regulating the particle size distribution of the resin particles.
2. Description of the Prior Art
Thermoplastic resins in finely-divided form have found use in a number of applications where it is either impossible or inconvenient to utilize the more conventional cube or pellet forms. For example, powdered organic polymeric thermoplastic resins in dry form have been used to coat articles by dip coating in either a static or fluidized bed, by powder coating wherein the powder is applied by spraying or dusting, and by flame spraying. In dispersed form, thermoplastic resin powders have been applied as coatings by roller coating, spray coating, slush coating, and dip coating to substrates such as metal, paper, paperboard, and the like. These powders have also been widely employed in conventional powder molding techniques. Other applications of these powders include paper pulp additives; mold release agents for rubber; additives to waxes, paints, and polishes; binders for non-woven fabrics; and so on.
It is known from U.S. Pat. No. 4,056,653 that spherical-shaped polymer particles having a rough surface can be prepared by shearing an ionomer resin in a closed shear zone under positive water pressure in the presence of a weak base, i.e., ammonia. The resulting spherical-shaped particles are said to possess an average diameter of from 10 to 100 microns and a packed density of greater than 32 lbs./ft..sup.3. For some applications of dispersed resin powders, it is often desirable to employ a powder size which is less than 10 microns or more than 100 microns.